Overnight Trouble?

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A nocturnal severe weather event is pretty unusual in southern New England but not unheard of. Tonight we have a set of ingredients that appears favorable for some severe weather from New Jersey up through eastern Massachusetts.

A powerful shortwave trough will race toward southern New England while a powerful low level jet develops overhead in response to strengthening synoptic scale/QG forcing.

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The question is how much instability will there be? We know that the atmosphere will be highly sheared (0-1km shear values in excess of 40 knots) but without the necessary instability the severe weather risk is low.

Our models have shown several different possibilities with the NAM and SREF remaining on the unstable side of things while the GFS has remained more modest.

SREF 3hr MLCAPE. Courtesy: Greg Carbin/SPC
SREF 3hr MLCAPE at KIJD | Courtesy: Greg Carbin/SPC

If moisture is able to stream north and moisten the boundary layer sufficiently, and lapse rates just above the boundary layer remain steep enough, enough CAPE will be present for severe thunderstorms and tornadoes tonight. The shear is even sufficient for a significant tornado in southern New England IF (and it’s a big IF) enough CAPE can be found. Damaging winds will also be possible with such strong winds just off the deck.

Stay weather aware late tonight- it could be an interesting morning!

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